US3806923A - Apparatus for rejecting radar signal noises - Google Patents

Apparatus for rejecting radar signal noises Download PDF

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Publication number
US3806923A
US3806923A US00339429A US33942973A US3806923A US 3806923 A US3806923 A US 3806923A US 00339429 A US00339429 A US 00339429A US 33942973 A US33942973 A US 33942973A US 3806923 A US3806923 A US 3806923A
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circuit
signals
distance
noises
signal
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S Tsuruta
K Kitazumi
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KYORITSU DEMPA CO Ltd
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KYORITSU DEMPA CO Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/28—Details of pulse systems
    • G01S7/285—Receivers
    • G01S7/292—Extracting wanted echo-signals
    • G01S7/2923—Extracting wanted echo-signals based on data belonging to a number of consecutive radar periods
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/28—Details of pulse systems
    • G01S7/285—Receivers
    • G01S7/34—Gain of receiver varied automatically during pulse-recurrence period, e.g. anti-clutter gain control

Definitions

  • Forelgn Apphcatlon Prlomy Data comprises, in combination; an automatic video level May 4, 1972 Japan 47-044334 setting circuit, wave form selecting circuit and coincidence checking circuit. These circuits, in combina- [52] US. Cl 343/7 A tion, are effective in rejecting white noises due to the [51 1 Int. Cl. G015 9/02 nature of water waves and especially in preventing tag. [58] Field of Search 343/5 AGC, 7 A get signals from being masked by back scattering sea clutter noises generated in short distance regions when [56] References Cited the sea is rough.
  • the present invention relates to an apparatus for rejecting noises from radar signals containing the'noises and more particularly to an apparatus for rejecting scattered and relfected noise radio waves from reflected signals containing the noise radio waves which, when radio waves are radiated from a radar equipment towards an object or target on the surface of the sea, are produced from part of the radiated radio waves due to being influenced by water waves and will disturb the reflected signals to make the identification thereof difficult,
  • radio waves in the form of a beam When radio waves in the form of a beam are radiated from a radar equipment towards a target on the surface of the sea, the radio waves will be reflected by the target to the equipmemt, accompanied with noise radio waves generated by the scattering and reflecting of part of the reflected radio waves due to the water waves (such noise radio waves being hereinafter referred to as sea clutter).
  • the noises are generated by the reflection of part of the radiated radio waves by the water waves which complicatedly vary in height, wavelength, frequency, shape, etc. depending upon the sea state and have effects on the noises accordingly. However, it is the wind speed that has the greatest effects on the noises.
  • the noise radio waves generated by the scattering and reflecting, by the water waves, of part of the radio waves in the form of a beam radiated from the radar equipment arrive at the radar equipment through a complicated multipath propagation to cause the equipment to generate a combined or resultant video voltage and, thus, the wave form thereof is deemed to conform to a random process.
  • the received wave from exhibited at a short range is such that the white noises by capillary waves and random-process (near Rayleigh distributed) noises by wind waves are superposed one upon another thereby forming a composite noise, while the received wave form exhibits an increasingly predominant presence of the randomprocess noises as the range increases.
  • the inside of a boundary, in which this change occurs, is referred to as a transition range and it increases as the wind speed is higher.
  • the screen of the cathode ray tube (hereinafter referred to as C.R.T.) of the radar set will thoroughly be brightened or masked at the approximately control part occupying a nearly circular and relatively large area of the screen whereby the target to be detected in the screen is made quite obscure and consequentially difficult to detect.
  • FIG. 1 is a diagram showing an example of target signals attended with sea clutter noises
  • FIG. 2 is a contour map of sea clutter noise voltages.
  • FIGS. 3 to 13 are diagrams showing embodiments of various elements constituting the present invention, among which FIG. 3 is a diagram for explaining the slicing of DC components of raw video signals,
  • FIG. 4 is a block diagram of an AGC bias voltage generator circuit for level setting
  • FIGS. 5 and 6 are diagrams for explaining the operation of the circuit in FIG. 4,
  • FIG. 7 is a diagram showing an example of raw video signals subjected to the level setting
  • FIG. 8 is a block diagram of a radar wave-form selecting circuit
  • FIG. 9 is a diagram for explaining the operation of the circuit in FIG. 8,
  • FIG. 10 is a block diagram of a signal checking circuit
  • FIG. 11 is a diagram for explaining the operation of the circuit in FIG. 10,
  • FIG. 12 is a block diagram of an instruction pulse generator circuit
  • FIG. 13 is a time chart for explaining the operation of the circuit in FIG. 12.
  • FIG. 14 is a general block diagram showing an embodiment of the present invention
  • FIG. 15 is a general block diagram showing another embodiment of the present invention.
  • FIG. 1 shows an example of target signals accompanied with sea clutter noises. They are unprocessed or raw video signalsobtained by detecting intermediatefrequency radar signals.
  • the abscissa in the figure represents distances (corresponding to times as which radio waves take to propagate forth and back between a radar equipment radiating the radar waves and a target to be detected), while the ordinate represents detected signal voltages.
  • P P, and P indicate reflected signals from the target.
  • the symbol a designates sea clutter noises conforming to (residing in) a random process b a portion where are concurrently present both sea clutter noises always existing as white noises and the above-mentioned random-process reflection noises, c an envelope defining the boundary of the white noises, c a transition range, at sea clutter noises at distances farther than the transition range, these noises being always present in the randomprocess manner, and g reflections from a land which is still farther situated.
  • the displayed region in which the white noises are displayed to exist varies with a change of sea states, especially water waves, influenced by the wind speed and, in addition, varies depending upon a direction in which the wind blows, such as up-wind direction, down-wind direction or cross-wind direction.
  • a direction in which the wind blows such as up-wind direction, down-wind direction or cross-wind direction.
  • FIG. 2 wherein the symbol 0 indicates the position of a radar as the original point and an arrow symbol W a direction in which the wind blows.
  • transition ranges are represented by contour lines, they increase while changing from f through f, to f, as the wind speed increases.
  • the transition ranges greatly increase with the increase in wind speed in the up-wind direction, while they do not do so greatly in the down-wind direction.
  • An object of the present invention is to provide an apparatus for rejecting noises thereby facilitating to detect a target and more particularly a noise rejecting apparatus for facilitating the detection of the target by suppressing the sensitivity correspondingly to the strength of white noises and for enhancing capability of distinguishing noises from reflected signals from the target by using the unique technique of selecting wave forms, even when the wind blows very hard and white noises generated are remarkably different in amount from each other depending on a direction in which the wind blows.
  • the object of the present invention is accomplished by the process comprising the following three means in combination:
  • the threshold voltage is lowered to such a level as E the region within the transition range C will be heavily masked, thereby making the target signal P, perfectly painted and the extraction thereof impossible. Further, in this case, increased noises will be displayed even in the region outside the transition range C and hence, the confirmation of the target signal will be difficult.
  • the white noises within the transition range C comprise DC component as indicated by the envelope c after the detection, a digital statistic processing (in which, for example, the presence and absence of a signal are represented by 1" and respectively) is impossible in the case of the threshold voltage E Therefore, in order to conduct such digital statistic processing without missing even small target signals, it is required that at least the white noises are suppressed so as to leave non-suppressed the random-process noises and the target signals.
  • FIG. 3 shows the wave forms of the rectified DC voltage of unprocessed video signals in the case where there occur white noises corresponding to the contour linef in FIG. 2.
  • the DC-voltage wave forms can be regarded as being substantially the same as the whitenoise envelope 0 in FIG. 1.
  • Noise voltages f and f in the up-wind and down-wind directions of the contour linef in FIG. 2 correspond to a full line f and a dotted line f in FIG. 3, respectively.
  • the noises on the contour line f in other directions or azimuths lie between the full line f and the dotted line f
  • bias voltages corresponding to the DC voltages in the respective angular directions or azimuths at the stage of variable-gain intermediate-frequency amplifier or the stage of variable-gain video amplifier after detection.
  • FIG. 4 shows a block diagram of an AGC bias voltage generating circuit for effecting the level setting.
  • an input signal 16 is the DC component of a video signal as obtained by rectifying the intermediate-frequency video signal, and is applied to several (three in the figure) slicers 22, 23 and 24.
  • the slicers slice the DC voltage of the video signal, namely, a component substantially corresponding to the envelope of white noises in the video signal, at the respective slice levels AB, 2 AE and 3 AE as illustrated in FIG. 3.
  • the outputs of the slicers 22, 23 and 24 are respectively fed to shift registers 25, 26 and 27, they are digitalized (for example, I being for the presence of the output of the slicer, while 0 for the absence thereof) under the control of clock pulses for distance counting which are applied during the sweep period, and they are registered while being sequentially shifted.
  • Each of the shift registers is made up of the same number of clock pulses generated during a time from the initiation of generation of master trigger pulse to the arrival of said pulses at a range to be swept.
  • With the shift register storage and read-out are simultaneously performed at the input end and output end thereof. When the register shifts the clock pulses over the maximum distance to be swept, it ceases its operation and waits for the next sweep initiation. This is shown in FIG. 5.
  • (A), (B) and (C) in the figure illustrate pulses corresponding to the DC-component voltages stored in the shift registers 25, 26 and 27, respectively.
  • the pulses stored in the shift registers are successively read out by the distance clock pulses generated at the next sweep initiation.
  • the read-out pulses are fed to the respective corresponding shaping circuits 28, 29 and 30, to be shaped into DC wave forms after passed through low-pass filter.
  • the shaped outputs are combined in a summing circuit 31. This is shown in FIG. 6.
  • FIG. 7 shows level set video signals obtained by suppressing the part of the white noises in the raw video signals in FIG. 1 to get said part almost lost while leaving intact only the target signals, the land echo and the randomprocess noises.
  • the means being the second one necessary for accomplishing the object of the present invention.
  • the target signal is a square wave whose rise is abrupt and whose fall is comparatively gentle, while the noises are distorted waves which are deemed to be composed at random of a number of quasi-sinusoidal waves, and marked points of peculiarity are not observed.
  • the pulse duration of the target signal is characterized by being generally wide in comparison with the halfwavelength of the sinusoidal wave of a frequency component of the maximum energy spectrum in the noise components.
  • the target signal has the property that, as the distance from the radar station becomes longer, the pulse width becomes somewhat narrower.
  • the noises exhibit the tendency that the random distribution state of the principal frequency components becomes gradually coarser.
  • the wave form selecting means of the present invention utilizes the distribution characteristics of the target signal and noises under analog states employing the distance as a parameter as described above, separates the signal and noises by wave form discrimination, and accept only the target signal.
  • a block diagram of the circuit arrangement of this means is shown in FIG. 8.
  • an input signal 33 consists of raw video signals subjected to the level setting (signals as in FIG. 7).
  • Numerals 34, 35 and 36 designate matched filters which are known.
  • the matched filter is one which is in an inversely functional relation to the wave form of the target signal, and it has the property of allowing the wave form of the target signal to pass therethrough most conveniently and preventing the wave forms of other different signals from passing therethrough.
  • the matched filter there are, for example, a selfcorrelation filter, a cross-correlation filter, and an optimum filter. All of them are circuits which extract the target signals from video signals composed of a mixture of the target signals and noises, by making use of the different wave forms of the signals between the noises.
  • matched filters of respectively having different characteristics corresponding to distance range regions. They are so connected as to be sequentially operated such that the matched filter 34 is used for the first distance region, the matched filter 35 for the next distance region, and the matched filter 36 for the subsequent distance region.
  • the delay time is varied depending on the distance between the radar and target.
  • the pulse duration is varied depending on the distance.
  • a circuit constant is varied depending on the distance.
  • Numeral 38 designates a band-pass or low-pass filter, 39, 40 and 41 flip-flops (hereinbelow denoted by FF), respectively, the numeral 2 a master trigger pulse-input terminal, and 18a, 18b and range gate pulses corresponding to the distance regions, respectively.
  • FF 39 is set, and its output actuates the matched filter 34 for the first distance region.
  • FF 39 is reset by application of the range gate pulse 18a, and the operation of the matched filter 34 is stopped.
  • FF 40 is set and its output starts the operation of the matched filter 35.
  • FF40 is provided with the range gate pulse 18b to be reset, and the operation of the matched filter 35 is stopped.
  • FF 41 is set and its output starts the operation of the matched filter 36.
  • the range gate pulse 18c is impressed to reset FF 4] and to accordingly stop the operation of the matched filter. 36.
  • the above operations are repeated by a sweep whose starting point is master trigger pulse at the succeeding radiation of radio waves.
  • the wave form selection is first performed in the analog state. Then, as in a wave form shown in FIG. 9(A), noises are markedly rejected in comparison with those of the wave form in FIG. 7. Further, pulse voltages exceeding the threshold voltage E are taken out (signal voltages are digitalized so that those above the threshold value may be represented by I, 'while those below the same may be indicated by o").
  • the digitalized wave form is illustrated in FIG. 9(8).
  • the wave form of (B) has the noises greatly rejected as compared with the wave form of (A).
  • the outputs of the respective matched filters are fed to an OR circuit 37 sequentially.
  • the output of the OR circuit is delivered as a digital video signal output 42 via the filter 38 to a processing circuit at the next stage.
  • FIG. 10 is a block diagram of a circuit arrangement for the method.
  • the digitalized video signals 42 of the first sweep are applied to a shift register 43, and simultaneously to an AND circuit 45.
  • the video signals 42 are applied in synchronism with clock pulses 17 which are impressed during the sweep period.
  • the shift register 43 also stores and shifts its contents in synchronism with the clock pulses 17.
  • the video signals corresponding to all the clock pulses in the sweep period have been stored, the shift is stopped, and the next sweep is waited for.
  • the video signals of this sweep are fed to the AND circuit 45 and the shift register 43, to initiate storage.
  • the video signals 46 having been stored at the first time are read out from the shift register 43 and are applied to the AND circuit 45 and a succeeding shift register 44, to initiate storage at the same time.
  • the shift is stopped, and the next sweep is awaited.
  • the video signals of this time are fed to the AND circuit 45 and the shift register 43, in which the storage of these signals and the read-out of the video signals of the second sweep are simultaneously carried out while both the signals are being shifted.
  • the signals 46 read out are applied to the AND circuit 45 and the shift register 44, in which they are stored. Simultaneously, video signals 47 of the first time are read out, and applied to the AND circuit 45 while being shifted.
  • the video signals obtained at the first, second and third times are simul' taneously applied to the AND circuit 45 while held in synchronism. Since outputs of logical products are derived herein, target signals existent at fixed distances are accepted; while noise pulses existent at distances in a random distance are rejected, whereby the video signal outputs remain composed only of the target signals. After the third sweep, only the target signals are accepted as the foregoing progress is being repeated to reject the noises.
  • FIG. 11 shows the time chart for the progress of extraction from the noise pulses and the cohered target signals, both being digitalized.
  • A in the figure illustrates the wave form of the third time of video signals 42 applied to the signal coincidence circuit in FIG. 10,
  • B the wave form of the second sweep of video signals 46 stored in the shift register 43 and read out therefrom, and
  • C the wave form of the first time of video signals 47 stored in the shift register 44 and read out therefrom.
  • D illustrates the wave form of accepted video signals in the case where all the video signals corresponding to the three sweeps are applied to the AND circuits 45 and processed by the logical product.
  • FIG. 12 A block diagram of a generator circuit for such instruction pulses is shown in FIG. 12.
  • numeral 19 designates distance clock pulses (hereinafter abbreviated to CP).
  • the circuitry is normally supplied with CP 19, and has its operation started in the following sequence for the first time when it receives the master trigger pulse 2 at the time of the radiation of radio waves.
  • FF flipflop
  • FF 56 flipflop
  • the counting of a batch counter 51 is initiated by C? 19 having passed through the gate 50.
  • the batch counter 51 is constructed such that, upon completion of counting of the number of pulses as required for the first distance region, it is reset by the output.
  • the output is transmitted as the distance. region pulse 18a, to simultaneously reset FF 56 to close the AND gate 50. In addition, it starts FF 57 for the next distance region.
  • An AND gate 52 is opened by the output of FF 57, and CPs 19 having passed through the gate 52 start to be counted by a batch counter 53. As soon as the counting of the number of pulses as required for this distance region is completed, the counting operation of the counter 53 is stopped by the output, and the output is transmitted as the distance region gate pulse 18b. Simultaneously therewith, it resets FF 57 to close an AND gate 52, and starts FF 58 for the next distance stage. An AND gate 54 is opened by the output of FF 58. CPs 19 having passed therethrough start to be counted by a batch counter 55. Upon completion of counting of the number of pulses as required for this distance region, the counting operation is stopped by the output.
  • the output is transmitted as the distance region gate pulse 180. Simultaneously therewith, it resets FF 58 to close the AND gate 54. In addition, it passes through an AND gate 61, to reset FF 59.
  • An AND gate 60 is opened by the output of FF 59 having started upon reception of the master trigger pulse 2, and allows CPs 19 to pass therethrough until it is closed after the generation of the distance region gate pulse 180. That is, the AND gate 60 has the function of delivering gated clock pulses (GCP) corresponding to the total pulses of all the distance regions.
  • GCP gated clock pulses
  • FIG. 13 shows a time chart of the various instruction pulses.
  • (I) in the figure illustrates the master trigger pulses 2 each indicating the time of the radiation of radio waves.
  • GCP gated clock pulses
  • FIG. 14 A block diagram of an embodiment of the present invention as includes these means, is shown in FIG. 14.
  • Intermediate-frequency video signal inputs from a radar receiver are entered from a terminal 1, and are applied to an intermediate-frequency amplifier 3 and an intermediate-frequency amplifier of variable gain 5.
  • the video signals amplified in the intermediate-frequency amplifier 3 have their DC component (of substantially the same shape as that of the envelope of white noises in the video signals) extracted in a rectifier circuit 4.
  • the DC component 16 is applied to an AGC voltage generator circuit 7.
  • the AGC voltage generator circuit is made up of the arrangement in FIG. 4.
  • the output voltage of the generator circuit 7 falls into the wave form as shown in FIG. 6(D), and is supplied as the AGC bias voltage of the intermediatefrequency amplifier 5.
  • the video signal inputs applied to the intermediate-frequency amplifier 5 are amplified under the state under which the DC component corresponding to the envelope of the white noises contained therein is suppressed by the bias voltage for AGC.
  • video signals subjected to level setting as shown in FIG. 7 are provided at the output of the detector 6.
  • the output is fed to a wave-form selecting circuit 10, and is processed therein.
  • the wave-form selecting circuit 10 is composed of a distance region matching filter 11, a video adder l2 and a filter 13.
  • the output of the discriminator 10 becomes digitalized video signals as in FIG. 9(B), and is delivered to a signal coincidence circuit 14 at the next stage.
  • the signal coincidence circuit 14 is known. As already explained with reference to FIGS. and 11, video signals having the sea clutter noises rejected and consisting only of the fixed target signals can be accepted by means of the circuit 14.
  • the AGC voltage generator circuit 7, wave-form selecting circuit 10 and signal coincidence circuit 14 are driven by application of the master trigger pulse from a terminal 2, and are operated by the various instruction pulses synchronized with CPs 19 from a clock pulse generator 8.
  • the instruction pulses are composed in an instruction pulse generator 9, and are obtained in the form of the gated clock pulses (GCP) l7 and distance stage gate pulses 18 (18a, 18b and 180). The particulars have been already described in detail with reference to FIGS. 12 and 13.
  • the apparatus shown in FIG. 14 receives as inputs the intermediate-frequency video signals of the radar receiver, the circuit of the stage of the intermediate-frequency amplification need be provided in the apparatus. However, it has the great advantage that no distortion occurs in the wave form of the output.
  • FIG. 15 shows a block diagram of another embodiment of the present invention.
  • the embodiment is of a simplified form of-the previous embodiment in FIG. 14, and can dispense with the intermediate-frequency amplification stage as detected video signals of the radar receiver are inputted thereto.
  • the apparatus since the level setting of the detected video signals is conducted, the apparatus is disadvantageous in bringing about slight distortion in the wave form of the output.
  • the same parts as in FIG. 14 are assigned with the same symbols.'
  • the video signals detected in the radar receiver are supplied from a terminal 20, and are applied to a variable-gain video amplifier 21 and the AGC voltage generator circuit 7.
  • Suitable as the variablegain video amplifier 21 is one having such property that the gain decreases with increase in the bias voltage, and is, for example, a logarithmic amplifier.
  • a DC component equivalent to the envelope of white noises in the detected video signals is sliced to digitalize signal voltages in a manner substantially the same as in the case of FIG. 14.
  • the digitalized signal voltages are applied to the video amplifier 21 as AGC bias voltages.
  • the other construction and operation are the same as in the case of FIG. 14.
  • the foregoing embodiments have been described as comprising in combination all the three means of the video signal level-selecting means, the wave-form selecting means and the signal coincidence means.
  • the apparatus can be put into practical use as a simplified system.
  • apparatus of a simple circuit arrangement is utilized for a marine radar receiver equipment, whereby an epoch-making target-signal extracting performance as compared with the performance of the prior-art receiver equipment can be attained.
  • radar signal noise rejection processing apparatus comprising: a circuit which rectifies intermediate-frequency video signal supplied from an intermediate-frequency amplification stage of said receiver, thereby to obtain a DC component corresponding to an envelope of white noises contained in said complex signals; an AGC bias voltage generator circuit which includes M (several) circuits which slice said DC component with M stages of voltage levels, sample the respective sliced outputs at every distance corresponding to-a period of clock pulses and turn them into digitalized signals in the binary number based on the presence and absence of signals, M shift registers which write and store, shift, and read out and output said digitalized signals of the respective stages over the entire distance ranges for one sweep period under control of said clock pulses, M shaping circuits which shape the digitalized pulse outputs read out from the respective shift registers, thereby to turn them into a DC output form of an analog quantity, and a summing circuit which combines outputs of the respective shaping circuits in level, to prepare a bias voltage for AGC; a variable-gain intermediate
  • the radar signal noise rejection processing apparatus characterized in that a waveform discriminating circuit is connected between said detector circuit and said signal checking circuit, said wave-form discriminating circuit comprising N matched filters which have target-signal extracting characteristics adapted for said respective distance regions with the whole sweep distance divided into N stages and which serve to extract target signals at said respective distance regions of said video signals of said detector circuit, and a circuit which adds the outputs of said N matched filters in distance.

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Radar Systems Or Details Thereof (AREA)
  • Image Processing (AREA)
  • Noise Elimination (AREA)
US00339429A 1972-05-04 1973-03-08 Apparatus for rejecting radar signal noises Expired - Lifetime US3806923A (en)

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FR2520512A1 (fr) * 1982-01-28 1983-07-29 Thomson Csf Dispositif d'elimination des retours de mer pour systeme radar
US20040062527A1 (en) * 2002-09-30 2004-04-01 Tokuji Kuroda Video signal recording apparatus
US20110291877A1 (en) * 2010-06-01 2011-12-01 Raytheon Company Methods and apparatus for non-isotropic sea clutter modeling
US8456352B2 (en) 2010-12-17 2013-06-04 Raytheon Company Methods and apparatus for automatic STC from sea state measurement via radar sea clutter eccentricity
US8456350B2 (en) 2010-12-17 2013-06-04 Raytheon Company Methods and apparatus for sea state measurement via radar sea clutter eccentricity
US20170343647A1 (en) * 2014-10-28 2017-11-30 Thales Method for processing a radar signal in land/sea detection mode; processing system and associated computer program product
RU208215U1 (ru) * 2021-06-02 2021-12-08 Федеральное государственное бюджетное образовательное учреждение высшего образования "Рязанский государственный радиотехнический университет имени В.Ф, Уткина" Режектор пассивных помех
RU208214U1 (ru) * 2021-06-07 2021-12-08 Федеральное государственное бюджетное образовательное учреждение высшего образования "Рязанский государственный радиотехнический университет имени В.Ф. Уткина" Вычислитель-режектор пассивных помех
RU209003U1 (ru) * 2021-05-31 2022-01-26 Федеральное государственное бюджетное образовательное учреждение высшего образования "Рязанский государственный радиотехнический университет имени В.Ф. Уткина" Фильтр режектирования помех
RU209015U1 (ru) * 2021-05-25 2022-01-28 Федеральное государственное бюджетное образовательное учреждение высшего образования "Рязанский государственный радиотехнический университет имени В.Ф. Уткина" Фильтр подавления помех
RU2765852C1 (ru) * 2021-04-12 2022-02-03 Федеральное государственное бюджетное образовательное учреждение высшего образования "Рязанский государственный радиотехнический университет имени В.Ф. Уткина" Фильтр режекции пассивных помех

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FR2520512A1 (fr) * 1982-01-28 1983-07-29 Thomson Csf Dispositif d'elimination des retours de mer pour systeme radar
EP0085628A1 (de) * 1982-01-28 1983-08-10 Thomson-Csf Anordnung zur Unterdrückung von Meeresechos in Radargeräten
US20040062527A1 (en) * 2002-09-30 2004-04-01 Tokuji Kuroda Video signal recording apparatus
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US20110291877A1 (en) * 2010-06-01 2011-12-01 Raytheon Company Methods and apparatus for non-isotropic sea clutter modeling
US8174435B2 (en) * 2010-06-01 2012-05-08 Raytheon Company Methods and apparatus for non-isotropic sea clutter modeling
US8456352B2 (en) 2010-12-17 2013-06-04 Raytheon Company Methods and apparatus for automatic STC from sea state measurement via radar sea clutter eccentricity
US8456350B2 (en) 2010-12-17 2013-06-04 Raytheon Company Methods and apparatus for sea state measurement via radar sea clutter eccentricity
US20170343647A1 (en) * 2014-10-28 2017-11-30 Thales Method for processing a radar signal in land/sea detection mode; processing system and associated computer program product
US10591583B2 (en) * 2014-10-28 2020-03-17 Thales Method for processing a radar signal in land/sea detection mode; processing system and associated computer program product
RU2765852C1 (ru) * 2021-04-12 2022-02-03 Федеральное государственное бюджетное образовательное учреждение высшего образования "Рязанский государственный радиотехнический университет имени В.Ф. Уткина" Фильтр режекции пассивных помех
RU209015U1 (ru) * 2021-05-25 2022-01-28 Федеральное государственное бюджетное образовательное учреждение высшего образования "Рязанский государственный радиотехнический университет имени В.Ф. Уткина" Фильтр подавления помех
RU209003U1 (ru) * 2021-05-31 2022-01-26 Федеральное государственное бюджетное образовательное учреждение высшего образования "Рязанский государственный радиотехнический университет имени В.Ф. Уткина" Фильтр режектирования помех
RU208215U1 (ru) * 2021-06-02 2021-12-08 Федеральное государственное бюджетное образовательное учреждение высшего образования "Рязанский государственный радиотехнический университет имени В.Ф, Уткина" Режектор пассивных помех
RU208214U1 (ru) * 2021-06-07 2021-12-08 Федеральное государственное бюджетное образовательное учреждение высшего образования "Рязанский государственный радиотехнический университет имени В.Ф. Уткина" Вычислитель-режектор пассивных помех

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JPS495588A (de) 1974-01-18
GB1399777A (en) 1975-07-02

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